Nutrient budgets for organic cropping systems - OFRF-funded project report by L. Drinkwater

Project Highlights

FERTILITY BUDGETS FOR ORGANIC GRAIN AND VEGETABLE SYSTEMS

On-farm nutrient budgets in organic cropping systems:
A tool for soil fertility management

Ithaca, NY - An assessment of the quantity of nutrients entering, leaving and remaining on a farm is the starting point for understanding nutrient cycling. When nutrient flows are documented for the entire rotation cycle, the resulting net balances can be used as a tool to help with soil management decisions and in the interpretation of soil tests.

Figure: Mass balance concept involves defining the management unit and measuring nutrient additions and harvested nutrient exports.

The long-term goal of this research is to develop tools that can be used by farmers to construct nutrient budgets for N, P and K in organic cash grain and vegetable production systems.

Researchers interviewed farmers to document their soil fertility management practices and sampled soil amendments and vegetable and grain crops at harvest for nutrient analysis, to assess the quantities of nutrients entering and leaving the farm. A series of databases were developed that can be used to support nutrient management decisions.

Results and practical applications:

A prototype nutrient budgeting tool was developed which would utilize these databases to construct multi-year budgets at the field and farm scale. This prototype tool currently exists in Excel spreadsheet format and is available in electronic form.
The sample budgets for the study sites suggest that the majority of organic vegetable production systems are adding significant surpluses of the major nutrients, as much as 180-200 kg P and N ha-1 yr-1 in excess.

For more details, please refer to the following links:
Drinkwater 03s16 Project Summary (4 pp) compiled by OFRF.

Laurie Drinkwater's complete (17 pp) project report: Drinkwater 03s16 Nutrient Budgets Complete Project Report

Principal investigator: Laurie Drinkwater, Associate Professor of Soil Ecology, Cornell University, Ithaca, NY 14853 tel. 607.255.9408 email led24@cornell.edu

Cooperating Investigators:
Anu Rangarajan, Assistant Professor, Fresh Market Vegetable Production, Department of Horticulture, Cornell University, Ithaca, NY;
Brian Caldwell, Farm Education Coordinator, Northeast Organic Farming Association of New York; Sarah Johnson, Executive Director, NOFA-New York

Farmer Avisors: Ann and Eric Nordell, Robin Ostfeld and Lou Johns, Jen and John Bokaer-Smith, Liza White and Andy Leed, Lisa and Brendan Bloodnick, Elizabeth Henderson, Dave and Kathy Rice, Klaas and Mary-Howell Martens, John Myer, Guy Christiansen, Ron Kirk, Larry Lewis, Marlin Martin, John and Chris Saeli, Fred Sepe

OFRF support for project: $23,840 with grant awards of $14,620 (spring 2003) and $9,220 (fall 2001)

Project Period: 2003-2004

Reported: January 2005